Subsea stations and installations have been contemplated for use in water depths beyond convenient diver working depths. Such subsea stations have been installed, maintained and operated by automatic, remote systems. Such prior subsea installations have been designed for single and multiple well requirements.
In subsea installations below depths at which divers may readily operate, installation, maintenance and operation of such installations, was accomplished by automatic, remote control means, remotely controlled robot devices, or by submarine devices. In many such prior subsea installations, connections of flowlines, power lines and various types of equipment usually required some relative horizontal movement of connector parts. Such relative horizontal movement of parts by remote control was often difficult because of the need for precise alignment, registration or orientation in a horizontal mode. Further, such prior subsea installations were inadequately protected from the hostile environment of the sea water, inadequately protected from subsea currents and movement of foreign matter by such currents. Maintenance and repair of a part of the installation often required shutdown of operating systems which were not directly associated with the part being repaired.
Solutions to some of the problems mentioned above are suggested by U.S. Pat. No. 3,633,667 which shows a multiple wellhead template provided with a wellhead unit and a production control unit, which were recoverable as units for maintenance and service. A subsea robot device movable about a wellhead on a rail is shown in U.S. Pat. No. 3,099,316.